Apparatus for forming drops



Oct. 25, 1966 J. J. STONE 3,281,859

APPARATUS FOR FORMING DROPS Filed Aug. 20, 1964 SOURCE 6 ox: OSULLATKDNS ELECTRO- \o MECHANICAL 24 TRANSDUCER \NK Q \/\DEO UNDER SKFJNAL PRESSURE souRcE 29/02 AET HELD POTENHAL SOURCE.

INK \NK u NDER UNDER PRESSURE PT2E$$URE SOURCE OF meH FREQ. CURRENT 0 w i?- 5 Z i 2 JOSEPH J sro/ws A FOP/V5) United States Patent M 3,281,859 APPARATUS FOR FORMING DROPS Joseph J. Stone, Glenview, Ill., assignor to A. B. Dick Company, Chicago, 11]., a corporation of Illinois Filed Aug. 20, 1964, Ser. No. 390,901 1 Claim. (Cl. 346-75) This invention relates to apparatus for producing the information represented by video signals using ink drops deposited on a writing medium, and more particularly to .improvements therein.

There has been developed apparatus for making a record on a writing medium, of the information represented by video signals, by generating a stream of ink drops, directing these ink drops toward a writing medium, and then deflecting the ink drops using video signals, in a manner so that when the ink drops do reach the writing medium they represent the information contained in the video signals. The apparatus which is employed for producing the ink drops consists of an ink reservoir in which there is ink under pressure. The ink reservoir feeds a pipe which is connected to a nozzle. An electromechanical transducer is employed to vibrate the pipe and nozzle at some suitable high frequency. The ink accordingly is ejected from the nozzle in a stream which shortly thereafter breaks into individual drops.

Because these drops are to be charged and thereafter deflected by electrical signals, it is desirable to make these drops have as uniform a size as possible. It is also desirable to form these drops with a close spacing, since the closer the spacing, the better the resolution which can be obtained. Also, it is desirable to form the drops into a small size so that the amplitude of the signals required to deflect them should not become excessive. The construction presently used for forming the ink drops comprises a metal nozzle which is vibrated by a means such as a separate electromagnetic transducer. This has not provided a satisfactory drop size uniformity or close spacing of the drops.

An object of this invention is to provide a unique drop forming structure.

Another object of this invention is to forming structure which allows drops to formly and closely spaced to one another.

Still another object of the present invention is the provision of an ink drop forming structure which is easy to manufacture and relatively inexpensive to build.

These and other objects of the invention are achieved provide a drop be formed uniby applying a magnetic field to a portion of the nozzle I near the end. A wire is attached to that portion of the nozzle in a manner so that it passes through the magnetic field at right angles thereto. Current is then applied to the wire with a frequency which it is desired that the nozzle be vibrated. Due to the well-known electrical motor effect, the wire and therefore the nozzle will vibrate in the magnetic field at the frequency of the current which is applied to the wire. the ink stream which is emitted from the nozzle with substantially uniform size and spacing and with a frequency which is synchronously related to the frequency of excitation.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claim. The invention itself both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

FIGURE 1 is a schematic drawing of an arrangement for ink drop recording in accordance with the prior art;

.Drops will therefore be formed in.

3,281,859 Patented Oct. 25, 1966 FIGURE 2 is a drawing of an embodiment of this invention; and

FIGURE 3 is a schematic of the circuitry which is required.

In order to alford a better understanding of this invention, a schematic drawing of ink drop recording apparatus in accordance with the prior art is shown in FIGURE 1 for the purpose of affording a better understanding of this invention. This apparatus comprises an ink reservoir 10 under pressure. Tubing 12 is connected to the ink reservoir 10 and terminates in a nozzle 14. An electromechanical transducer 16 vibrates the tubing and the nozzle in response to the output of the source of oscillation 18. The source of oscillation may be a source at a frequency which may vary from 5 kc. to kc. Near the tip of the nozzle 14 the ink is emitted as a solid stream 20 which, however, shortly thereafter breaks into drops such as 22. A charging tunnel 26 consisting of a conductive tube shown open for the sake of illustration, is positioned so that the ink drops which are formed pass therethrough. The video signal source 24 has its output connected to the conductive tubing 12 and the charging tunnel 26 as a result of which each drop 22 assumes a charge whose amplitude is proportional to the video signal applied between the charging tunnel 26 and the tubing 12 at the time that the drop is passing through the tubing 26.

The charged drops then continue in a path toward the moving paper 36. However, before they reach the paper, they pass between two spaced parallel plate electrodes 30, 32 to which a fixed potential is applied from a field potential source 34. The charged droplets thus are caused to enter an electric field established between the plates 30, 32 as a result of which each droplet is deflected from the path it would take in the absence of the electric field, an amount determined by the charge thereon. Accordingly, as the paper 36 is continuously moved, a line is drawn thereon whose shape or curvature is determined by the signals from the video signal source. In effect therefor, the recording on the paper is representative of the information conveyed by the video signals. As described thus far, this apparatus is known and does not constitute a part of this invention.

As shown in FIGURE 2, a hollow tube 40 has one end 42 formed in the shape of a nozzle. That is, the opening of the tube is reduced to a diameter on the order of the diameter desired for the drops 44 which are formed by the tube. Ink is applied to the other end of the tube 40. A wire 46 is attached to the tube 40 near the end 42, by any suitable means, such as by soldering, welding, or gluing. As shown in FIGURE 3, the Wire 46 is connected to a source of high frequency current 48 which causes current to flow through the wire at a desired frequency.

A magnet 50 is positioned on either side of the wire so that it is in and at right angles to the magnetic flux lines of the magnetic field of the magnet. Because of the current flow therethrough, the wire is caused to vibrate whereby the tube 40 vibrates therewith. As a result of the vibration of the tube, the ink flowing out of the nozzle end breaks up into drops which are spaced and formed synchronously with the frequency of vibration of the tube 40.

The simplicity of the device for forming droplets should be apparent from the foregoing description. The rate of vibration of the tube and therewith the rate of formation of the droplets may easily be varied by varying the frequency of excitation of the wire 46. Because of the simplicity of the device, there are fewer parts to break down and require replacement.

Accordingly, there has been described and shown herein a novel and simple arrangement for forming substantially uniformly sized and substantially uniformly spaced ink drops.

What is claimed is:

Apparatus to which ink is applied under pressure for the purpose of forming ink drops comprising a hollow tube having one end to which said ink under pressure is applied, said other end having the diameter thereof reduced to provide an opening through which the ink applied to said tube is emitted, a magnet positioned to establish a magnetic field transversely through a portion of said tube, a Wire attached to said tube in the region of said magnetic field, and means for applying current to said Wire at a predetermined frequency to vibrate said ink which is emitted from the reduced opening portion of said tube is formed into drops.

References Cited by the Examiner UNITED STATES PATENTS 2,512,743 6/1950 Hansell 346132 X 2,600,129 6/1952 Richards 346--75 2,600,822 6/1952 Yarnall et a1. 346-69 2,908,443 10/ 1959 Fruengel 2394 X 10 3,039,696 6/1962 Point et a1. 239102 X RICHARD B. WILKINSON, Primary Examiner.

LEO SMILOW, Examiner.

wire and tube at said predetermined frequency whereby 15 J. G. MURRAY, Assistant Examiner. 

